/*****************************************************************************
#                                                                            #
#    uStreamer - Lightweight and fast MJPG-HTTP streamer.                    #
#                                                                            #
#    Copyright (C) 2018-2021  Maxim Devaev <mdevaev@gmail.com>               #
#                                                                            #
#    This program is free software: you can redistribute it and/or modify    #
#    it under the terms of the GNU General Public License as published by    #
#    the Free Software Foundation, either version 3 of the License, or       #
#    (at your option) any later version.                                     #
#                                                                            #
#    This program is distributed in the hope that it will be useful,         #
#    but WITHOUT ANY WARRANTY; without even the implied warranty of          #
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           #
#    GNU General Public License for more details.                            #
#                                                                            #
#    You should have received a copy of the GNU General Public License       #
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.  #
#                                                                            #
*****************************************************************************/


#include <stdint.h>
#include <stdbool.h>
#include <stdatomic.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <assert.h>

#include <sys/mman.h>
#include <sys/stat.h>
#include <linux/videodev2.h>

#include <pthread.h>
#include <jansson.h>
#include <janus/config.h>
#include <janus/plugins/plugin.h>

#include "config.h"
#include "tools.h"
#include "threading.h"
#include "list.h"
#include "memsinksh.h"

#include "rtp.h"


static int _plugin_init(janus_callbacks *gw, const char *config_file_path);
static void _plugin_destroy(void);

static void _plugin_create_session(janus_plugin_session *session, int *error);
static void _plugin_destroy_session(janus_plugin_session *session, int *error);
static json_t *_plugin_query_session(janus_plugin_session *session);

static void _plugin_setup_media(janus_plugin_session *session);
static void _plugin_hangup_media(janus_plugin_session *session);

static struct janus_plugin_result *_plugin_handle_message(
	janus_plugin_session *session, char *transaction, json_t *msg, json_t *jsep);

static int _plugin_get_api_compatibility(void);
static int _plugin_get_version(void);
static const char *_plugin_get_version_string(void);
static const char *_plugin_get_description(void);
static const char *_plugin_get_name(void);
static const char *_plugin_get_author(void);
static const char *_plugin_get_package(void);


#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Woverride-init"
static janus_plugin _plugin = JANUS_PLUGIN_INIT(
	.init = _plugin_init,
	.destroy = _plugin_destroy,

	.create_session = _plugin_create_session,
	.destroy_session = _plugin_destroy_session,
	.query_session = _plugin_query_session,

	.setup_media = _plugin_setup_media,
	.hangup_media = _plugin_hangup_media,

	.handle_message = _plugin_handle_message,

	.get_api_compatibility = _plugin_get_api_compatibility,
	.get_version = _plugin_get_version,
	.get_version_string = _plugin_get_version_string,
	.get_description = _plugin_get_description,
	.get_name = _plugin_get_name,
	.get_author = _plugin_get_author,
	.get_package = _plugin_get_package,
);
#pragma GCC diagnostic pop

janus_plugin *create(void) { // cppcheck-suppress unusedFunction
	return &_plugin;
}


typedef struct _client_sx {
	janus_plugin_session *session;
	bool transmit;

	LIST_STRUCT(struct _client_sx);
} _client_s;


static char				*_g_memsink_obj = NULL;
const long double		_g_wait_timeout = 1;
const long double		_g_lock_timeout = 1;
const useconds_t		_g_lock_polling = 1000;
const useconds_t		_g_watchers_polling = 100000;

static _client_s		*_g_clients = NULL;
static janus_callbacks	*_g_gw = NULL;
static rtp_s			*_g_rtp = NULL;

static pthread_t		_g_tid;
static pthread_mutex_t	_g_lock = PTHREAD_MUTEX_INITIALIZER;
static atomic_bool		_g_ready = ATOMIC_VAR_INIT(false);
static atomic_bool		_g_stop = ATOMIC_VAR_INIT(false);
static atomic_bool		_g_has_watchers = ATOMIC_VAR_INIT(false);


#define JLOG_INFO(_msg, ...)	JANUS_LOG(LOG_INFO, "== %s -- " _msg "\n", _plugin_get_name(), ##__VA_ARGS__)
#define JLOG_WARN(_msg, ...)	JANUS_LOG(LOG_WARN, "== %s -- " _msg "\n", _plugin_get_name(), ##__VA_ARGS__)
#define JLOG_ERROR(_msg, ...)	JANUS_LOG(LOG_ERR, "== %s -- " _msg "\n", _plugin_get_name(), ##__VA_ARGS__)

#define JLOG_PERROR(_msg, ...) { \
		char _perror_buf[1024] = {0}; \
		char *_perror_ptr = errno_to_string(errno, _perror_buf, 1023); \
		JANUS_LOG(LOG_ERR, "[%s] " _msg ": %s\n", _plugin_get_name(), ##__VA_ARGS__, _perror_ptr); \
	}

#define LOCK			A_MUTEX_LOCK(&_g_lock)
#define UNLOCK			A_MUTEX_UNLOCK(&_g_lock)
#define READY			atomic_load(&_g_ready)
#define STOP			atomic_load(&_g_stop)
#define HAS_WATCHERS	atomic_load(&_g_has_watchers)


static void _relay_rtp_clients(const uint8_t *datagram, size_t size) {
	janus_plugin_rtp packet = {
		.video = true,
		.buffer = (char *)datagram,
		.length = size,
	};
	janus_plugin_rtp_extensions_reset(&packet.extensions);
	LIST_ITERATE(_g_clients, client, {
		if (client->transmit) {
			_g_gw->relay_rtp(client->session, &packet);
		}
	});
}

static int _wait_frame(int fd, memsink_shared_s* mem, uint64_t last_id) {
	long double deadline_ts = get_now_monotonic() + _g_wait_timeout;
	long double now;
	do {
		int retval = flock_timedwait_monotonic(fd, _g_lock_timeout);
		now = get_now_monotonic();
		if (retval < 0 && errno != EWOULDBLOCK) {
			JLOG_PERROR("Can't lock memsink");
			return -1;
		} else if (retval == 0) {
			if (mem->magic == MEMSINK_MAGIC && mem->version == MEMSINK_VERSION && mem->id != last_id) {
				return 0;
			}
			if (flock(fd, LOCK_UN) < 0) {
				JLOG_PERROR("Can't unlock memsink");
				return -1;
			}
		}
		usleep(_g_lock_polling);
	} while (now < deadline_ts);
	return -2;
}

static int _get_frame(int fd, memsink_shared_s *mem, frame_s *frame, uint64_t *frame_id) {
	frame_set_data(frame, mem->data, mem->used);
	FRAME_COPY_META(mem, frame);
	*frame_id = mem->id;
	mem->last_client_ts = get_now_monotonic();
	int retval = 0;
	if (frame->format != V4L2_PIX_FMT_H264) {
		JLOG_ERROR("Got non-H264 frame from memsink");
		retval = -1;
	}
	if (flock(fd, LOCK_UN) < 0) {
		JLOG_PERROR("Can't unlock memsink");
		retval = -1;
	}
	return retval;
}

static void *_clients_thread(UNUSED void *arg) {
	A_THREAD_RENAME("us_clients");
	atomic_store(&_g_ready, true);

	frame_s *frame = frame_init();
	uint64_t frame_id = 0;

	unsigned error_reported = 0;

#	define IF_NOT_REPORTED(_error, ...) { \
			if (error_reported != _error) { __VA_ARGS__; error_reported = _error; } \
		}

	while (!STOP) {
		if (!HAS_WATCHERS) {
			IF_NOT_REPORTED(1, {
				JLOG_INFO("No active watchers, memsink disconnected");
			});
			usleep(_g_watchers_polling);
			continue;
		}

		int fd = -1;
		memsink_shared_s *mem = NULL;

		if ((fd = shm_open(_g_memsink_obj, O_RDWR, 0)) <= 0) {
			IF_NOT_REPORTED(2, {
				JLOG_PERROR("Can't open memsink");
			});
			goto close_memsink;
		}

		if ((mem = memsink_shared_map(fd)) == NULL) {
			IF_NOT_REPORTED(3, {
				JLOG_PERROR("Can't map memsink");
			});
			goto close_memsink;
		}

		error_reported = 0;

		JLOG_INFO("Memsink opened; reading frames ...");
		while (!STOP && HAS_WATCHERS) {
			int result = _wait_frame(fd, mem, frame_id);
			if (result == 0) {
				if (_get_frame(fd, mem, frame, &frame_id) != 0) {
					goto close_memsink;
				}
				LOCK;
				rtp_wrap_h264(_g_rtp, frame, _relay_rtp_clients);
				UNLOCK;
			} else if (result == -1) {
				goto close_memsink;
			}
		}

		close_memsink:
			if (mem != NULL) {
				JLOG_INFO("Memsink closed");
				memsink_shared_unmap(mem);
				mem = NULL;
			}
			if (fd > 0) {
				close(fd);
				fd = -1;
			}
			sleep(1); // error_delay
	}

#	undef IF_NOT_REPORTED

	frame_destroy(frame);
	return NULL;
}

static int _read_config(const char *config_dir_path) {
	char *config_file_path;
	janus_config *config = NULL;

	A_ASPRINTF(config_file_path, "%s/%s.jcfg", config_dir_path, _plugin_get_package());
	JLOG_INFO("Reading config file '%s' ...", config_file_path);

	config = janus_config_parse(config_file_path);
	if (config == NULL) {
		JLOG_ERROR("Can't read config");
		goto error;
	}
	janus_config_print(config);

	janus_config_category *config_memsink = janus_config_get_create(config, NULL, janus_config_type_category, "memsink");
	janus_config_item *config_memsink_obj = janus_config_get(config, config_memsink, janus_config_type_item, "object");
	if (config_memsink_obj == NULL || config_memsink_obj->value == NULL || config_memsink_obj->value[0] == '\0') {
		JLOG_ERROR("Missing config value: memsink.object");
		goto error;
	}
	_g_memsink_obj = strdup(config_memsink_obj->value);

	int retval = 0;
	goto ok;
	error:
		retval = -1;
	ok:
		if (config) {
			janus_config_destroy(config);
		}
		free(config_file_path);
		return retval;
}

static int _plugin_init(janus_callbacks *gw, const char *config_dir_path) {
	// https://groups.google.com/g/meetecho-janus/c/xoWIQfaoJm8
	// sysctl -w net.core.rmem_default=500000 
	// sysctl -w net.core.wmem_default=500000 
	// sysctl -w net.core.rmem_max=1000000 
	// sysctl -w net.core.wmem_max=1000000

	JLOG_INFO("Initializing plugin ...");
	assert(!READY);
	assert(!STOP);
	if (gw == NULL || config_dir_path == NULL || _read_config(config_dir_path) < 0) {
		return -1;
	}
	_g_gw = gw;
	_g_rtp = rtp_init();
	A_THREAD_CREATE(&_g_tid, _clients_thread, NULL);
	return 0;
}

static void _plugin_destroy(void) {
	JLOG_INFO("Destroying plugin ...");
	atomic_store(&_g_stop, true);
	if (READY) {
		A_THREAD_JOIN(_g_tid);
	}

	LIST_ITERATE(_g_clients, client, {
		LIST_REMOVE(_g_clients, client);
		free(client);
	});
	_g_clients = NULL;

	rtp_destroy(_g_rtp);
	_g_rtp = NULL;

	_g_gw = NULL;

	if (_g_memsink_obj) {
		free(_g_memsink_obj);
		_g_memsink_obj = NULL;
	}
}

#define IF_DISABLED(...) { if (!READY || STOP) { __VA_ARGS__ } }

static void _plugin_create_session(janus_plugin_session *session, int *error) {
	IF_DISABLED({ *error = -1; return; });
	LOCK;
	JLOG_INFO("Creating session %p ...", session);
	_client_s *client;
	A_CALLOC(client, 1);
	client->session = session;
	client->transmit = true;
	LIST_APPEND(_g_clients, client);
	atomic_store(&_g_has_watchers, true);
	UNLOCK;
}

static void _plugin_destroy_session(janus_plugin_session* session, int *error) {
	IF_DISABLED({ *error = -1; return; });
	LOCK;
	bool found = false;
	bool has_watchers = false;
	LIST_ITERATE(_g_clients, client, {
		if (client->session == session) {
			JLOG_INFO("Removing session %p ...", session);
			LIST_REMOVE(_g_clients, client);
			free(client);
			found = true;
		} else {
			has_watchers = (has_watchers || client->transmit);
		}
	});
	if (!found) {
		JLOG_WARN("No session %p", session);
		*error = -2;
	}
	atomic_store(&_g_has_watchers, has_watchers);
	UNLOCK;
}

static json_t *_plugin_query_session(janus_plugin_session *session) {
	IF_DISABLED({ return NULL; });
	json_t *info = NULL;
	LOCK;
	LIST_ITERATE(_g_clients, client, {
		if (client->session == session) {
			info = json_string("session_found");
			break;
		}
	});
	UNLOCK;
	return info;
}

static void _set_transmit(janus_plugin_session *session, UNUSED const char *msg, bool transmit) {
	IF_DISABLED({ return; });
	LOCK;
	bool found = false;
	bool has_watchers = false;
	LIST_ITERATE(_g_clients, client, {
		if (client->session == session) {
			client->transmit = transmit;
			//JLOG_INFO("%s session %p", msg, session);
			found = true;
		}
		has_watchers = (has_watchers || client->transmit);
	});
	if (!found) {
		JLOG_WARN("No session %p", session);
	}
	atomic_store(&_g_has_watchers, has_watchers);
	UNLOCK;
}

#undef IF_DISABLED

static void _plugin_setup_media(janus_plugin_session *session) { _set_transmit(session, "Unmuted", true); }
static void _plugin_hangup_media(janus_plugin_session *session) { _set_transmit(session, "Muted", false); }

static struct janus_plugin_result *_plugin_handle_message(
	janus_plugin_session *session, char *transaction, json_t *msg, json_t *jsep) {

	assert(transaction != NULL);

#	define FREE_MSG_JSEP { \
			if (msg) json_decref(msg); \
			if (jsep) json_decref(jsep); \
		}

	if (session == NULL || msg == NULL) {
		free(transaction);
		FREE_MSG_JSEP;
		return janus_plugin_result_new(JANUS_PLUGIN_ERROR, (msg ? "No session" : "No message"), NULL);
	}

#	define PUSH_ERROR(_error, _reason) { \
			/*JLOG_ERROR("Message error in session %p: %s", session, _reason);*/ \
			json_t *_event = json_object(); \
			json_object_set_new(_event, "ustreamer", json_string("event")); \
			json_object_set_new(_event, "error_code", json_integer(_error)); \
			json_object_set_new(_event, "error", json_string(_reason)); \
			_g_gw->push_event(session, &_plugin, transaction, _event, NULL); \
			json_decref(_event); \
		}

	json_t *request_obj = json_object_get(msg, "request");
	if (request_obj == NULL) {
		PUSH_ERROR(400, "Request missing");
		goto ok_wait;
	}

	const char *request_str = json_string_value(request_obj);
	if (!request_str) {
		PUSH_ERROR(400, "Request not a string");
		goto ok_wait;
	}
	//JLOG_INFO("Message: %s", request_str);

#	define PUSH_STATUS(_status, _jsep) { \
			json_t *_event = json_object(); \
			json_object_set_new(_event, "ustreamer", json_string("event")); \
			json_t *_result = json_object(); \
			json_object_set_new(_result, "status", json_string(_status)); \
			json_object_set_new(_event, "result", _result); \
			_g_gw->push_event(session, &_plugin, transaction, _event, _jsep); \
			json_decref(_event); \
		}

	if (!strcmp(request_str, "start")) {
		PUSH_STATUS("started", NULL);

	} else if (!strcmp(request_str, "stop")) {
		PUSH_STATUS("stopped", NULL);

	} else if (!strcmp(request_str, "watch")) {
		char *sdp = rtp_make_sdp(_g_rtp);
		if (sdp == NULL) {
			PUSH_ERROR(503, "Haven't received SPS/PPS from memsink yet");
			goto ok_wait;
		}
		//JLOG_INFO("SDP generated:\n%s", sdp);
		json_t *offer_jsep = json_pack("{ssss}", "type", "offer", "sdp", sdp);
		free(sdp);
		PUSH_STATUS("started", offer_jsep);
		json_decref(offer_jsep);

	} else {
		PUSH_ERROR(405, "Not implemented");
	}

	ok_wait:
		FREE_MSG_JSEP;
		return janus_plugin_result_new(JANUS_PLUGIN_OK_WAIT, NULL, NULL);

#	undef PUSH_ERROR
#	undef FREE_MSG_JSEP
}

static int _plugin_get_api_compatibility(void)		{ return JANUS_PLUGIN_API_VERSION; }
static int _plugin_get_version(void)				{ return VERSION_U; }
static const char *_plugin_get_version_string(void)	{ return VERSION; }
static const char *_plugin_get_description(void)	{ return "Pi-KVM uStreamer Janus plugin for H.264 video"; }
static const char *_plugin_get_name(void)			{ return "ustreamer"; }
static const char *_plugin_get_author(void)			{ return "Maxim Devaev <mdevaev@gmail.com>"; }
static const char *_plugin_get_package(void)		{ return "janus.plugin.ustreamer"; }


#undef STOP
#undef READY
#undef UNLOCK
#undef LOCK

#undef JLOG_PERROR
#undef JLOG_ERROR
#undef JLOG_WARN
#undef JLOG_INFO